1. Field of the Invention:
This invention relates to a rolling bearing for a strut-type suspension. More specifically, the present invention concerns a shell-type ball bearing through which a piston rod of a shock absorber of a motor vehicle can be inserted.
2. Prior Art:
Strut-type suspensions for motor vehicles are well known. Typifying such suspensions is that shown in FIG. 3 of the drawing. Generally, prior art strut-type suspensions include a piston rod 10' associated with a shock absorber. The piston rod 10' is inserted through an opening in a rotary bearing race 3' of a ball bearing 2' and the inner face of an upper seat 11' for a coil spring 13'. The seal 11' carries the lower axial end of the rotary race 3'. The rotary race 3' is fixed in position on the shoulder of the piston rod 10'. These two members are fixed tightly to the piston rod 10'.
Ordinarily, according to the prior art the coil spring 13' is disposed between the upper spring seat 11' and a lower seat (not shown) which receives or seats the opposite end of the spring 13'. The lower seat is fixedly attached to an outer cylinder of the shock absorber such that the coil spring 13' encircles the piston rod 10'. A stationary bearing race 4' of the ball bearing 2' is fixed in position to a lower plate 15' of a shock absorbing rubber buffer mount assembly 14'. The buffer mount 14' comprises an integrally formed upper plate 16', the lower plate 15' and a rubber buffer 17' interposed between the upper plate 16' and the lower plate 15'. The buffer 17' is integrally adhered to the two plates 15' and 16' by vulcanizing. The upper plate 16' is attached by a bolt 19' to a mounting plate 18' of the motor vehicle. Usually a dust cover 20' is incorporated into the structure.
When the wheels of a vehicle are turned in a different direction by the steering wheel of the vehicle, the piston rods 10' of the vehicle shock absorbers will also rotate, along with the outer cylinders of the piston rods 10'. Thus, both a radial load and a thrust load, applied to each shock absorber, can be supported by the ball bearing 2' associated therewith.
As explained above, ordinary type bearing perform, both, as a thrust bearing and a radial bearing. However, it is increasingly required to use ball bearings of relatively larger size having larger bearing width in order to obtain a predetermined increased loading capacity. In order to achieve this the stroke length of the shock absorber must be shortened, due to the limited mounting height allowed for the bearing. This decreases the extent of shock absorbing capacity.
Use of a shell-type needle roller bearing having a considerably small bearing width may solve the aforesaid problem to some extent. However, such prior art needle roller bearings result in worse steering performance. This is attributable to the larger torque required by the use of needle roller bearing.
In British Patent Specification No. 1446000 there is disclosed a rolling bearing for suspension struts which can solve many of these problems mentioned above. However, the bearing in the British Patent still cannot avoid mutual metal-to-metal contact in the axial direction, between the stationary bearing race and the rotary bearing race, in the assembly, due to the vibration of the vehicle to which the struts are applied. Hence, there is encountered various wear breakage at the points to contact, together with damage to the rubber buffer mount caused by metal powders formed by the wear breakage. This creates various undesirable effects on the durability of the suspension struts.
The present invention, as will subsequently be described, solves such drawbacks in the prior art strut-type suspension.